Independent Orbiter Assessment (IOA): Assessment of the manned maneuvering unit

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA effort first completed an analysis of the Manned Maneuvering Unit (MMU) hardware, generating draft failure modes and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contain within the NASA FMEA/CIL documentation. The IOA results were then compared to the proposed Martin Marietta FMEA/CIL Post 51-L updates. A discussion of each discrepancy from the comparison is provided through additional analysis as required. These discrepancies were flagged as issues, and recommendations were made based on the FMEA data available at the time. The results of this comparison for the Orbiter MMU hardware are documented. The IOA product for the MMU analysis consisted of 204 failure mode worksheets that resulted in 95 potential critical items being identified. Comparison was made to the NASA baseline which consisted of 179 FMEAs and 110 CIL items. This comparison produced agreement on all 121 FMEAs which caused differences in 92 CIL items

Independent Orbiter Assessment (IOA): Analysis of the atmospheric revitalization pressure control subsystem

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis/Critical Items List (FMEA/CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results corresponding to the Orbiter Atmospheric Revitalization and Pressure Control Subsystem (ARPCS) are documented. The ARPCS hardware was categorized into the following subdivisions: (1) Atmospheric Make-up and Control (including the Auxiliary Oxygen Assembly, Oxygen Assembly, and Nitrogen Assembly); and (2) Atmospheric Vent and Control (including the Positive Relief Vent Assembly, Negative Relief Vent Assembly, and Cabin Vent Assembly). The IOA analysis process utilized available ARPCS hardware drawings and schematics for defining hardware assemblies, components, and hardware items. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode

Improving the Functional Control of Aged Ferroelectrics using Insights from Atomistic Modelling

We provide a fundamental insight into the microscopic mechanisms of the ageing processes. Using large scale molecular dynamics simulations of the prototypical ferroelectric material PbTiO3, we demonstrate that the experimentally observed ageing phenomena can be reproduced from intrinsic interactions of defect-dipoles related to dopant-vacancy associates, even in the absence of extrinsic effects. We show that variation of the dopant concentration modifies the material's hysteretic response. We identify a universal method to reduce loss and tune the electromechanical properties of inexpensive ceramics for efficient technologies.Comment: 6 pages, 3 figure

Independent Orbiter Assessment (IOA): Assessment of the life support and airlock support systems, volume 1

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA effort first completed an analysis of the Life Support and Airlock Support Systems (LSS and ALSS) hardware, generating draft failure modes and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The IOA results were then compared to the NASA FMEA/CIL baseline with proposed Post 51-L updates included. The discrepancies were flagged for potential future resolution. This report documents the results of that comparison for the Orbiter LSS and ALSS hardware. The IOA product for the LSS and ALSS analysis consisted of 511 failure mode worksheets that resulted in 140 potential critical items. Comparison was made to the NASA baseline which consisted of 456 FMEAs and 101 CIL items. The IOA analysis identified 39 failure modes, 6 of which were classified as CIL items, for components not covered by the NASA FMEAs. It was recommended that these failure modes be added to the NASA FMEA baseline. The overall assessment produced agreement on all but 301 FMEAs which caused differences in 111 CIL items

Hemp-lime: highlighting room for improvement

Greenhouse Gas Emissions and growing energy demands are global issues that are exacerbated by the construction industry; an industry whose activities make up the majority of most country’s emissions, while the Housing Sector alone expends 60% of its total energy consumption on space heating of buildings [1]. Materials are continually being developed to be more environmentally friendly and reduce the carbon foot-print of buildings. Hemp-lime is a natural material that sequesters CO2 during growth of the hemp plant through photosynthesis; this reduces the material’s carbon footprint, allowing potential construction of ‘zero carbon’ buildings. The simple homogeneous construction of a hemp-lime building exhibits a good thermal performance, which can dampen fluctuations in external temperature and passively control internal humidity. This considerably reduces the demand on internal heating and cooling thus reducing the energy consumed within the building. Hemp-lime construction can be conducted in a number of ways including manual placement and spraying. This paper outlines some of the issues arising from differing construction methods, highlighting gaps in the knowledge and understanding of the use of this natural material. The paper concludes by presenting topics for further research in order to improve and promote hemp-lime use within the construction sector

Early out-of-equilibrium beam-plasma evolution

We solve analytically the out-of-equilibrium initial stage that follows the injection of a radially finite electron beam into a plasma at rest and test it against particle-in-cell simulations. For initial large beam edge gradients and not too large beam radius, compared to the electron skin depth, the electron beam is shown to evolve into a ring structure. For low enough transverse temperatures, the filamentation instability eventually proceeds and saturates when transverse isotropy is reached. The analysis accounts for the variety of very recent experimental beam transverse observations.Comment: to appear in Phys. Rev. Letter